THE ROUNDHEADED APPLE-TREE BORER. 3 
enough, this line, except in its southwestern extent, bounds also rather 
definitely the distribution in America of the service tree,’ which is 
one of the borer’s favorite host trees. 
Throughout the range of this insect there are many restricted 
localities where it does not occur, or, at least, is so rare as to have 
escaped notice. It is not uncommon to find the borers exceedingly 
abundant in one orchard while in other orchards, perhaps not more 
than a mile away, it may never have appeared in sufficient numbers 
to have attracted attention. This tendency of the species to be pres- 
ent in one locality and absent in an adjoining one is an interesting 
phase of its distribution. It has been noticed that where soil condi- 
tions and other causes favor an abundant growth of wild trees in 
which the borers breed, near-by cultivated trees will suffer more than 
where such natural breeding places are not present. 
Asa rule the parent female beetle in ovipositing does not move far 
from the tree in which she was developed, providing there are suit- 
able trees near by in which she can place her eggs. (Fig. 3.) This 
tendency of the female to spend her adult life and provide for her 
progeny within a restricted area accounts very largely for the irregu- 
larity in the local occurrence of the borers. An adult female issuing 
in an orchard is quite likely to deposit all her eggs within a few rods 
of her host tree; thus it is that in infested orchards that have not 
been entirely neglected in respect to this pest the borers are likely to 
be found infesting groups of half a dozen or more trees standing 
close together. It is a common observation, especially in newly 
planted orchards, that the trees standing near to woods in which 
service, wild crab, or mountain ash trees grow, or those adjacent to 
old infested orchards, are the ones to be first attacked by the borers. 
This is so because the woods and neglected orchards are breeding 
places for the borers, and when the adult insects appear they select 
the near-by orchard trees for attack. This is an important point to 
keep in mind in the work of ridding orchards of, and keeping them 
free from this pest. 
FOOD PLANTS. 
This borer, so far as is known, confines its attacks to a few species 
of trees belonging to the family Rosaceew. Even among the limited 
number of its host plants the insect shows considerable discrimina- 
tion, greatly preferring as food some species of trees above others. 
Of our cultivated fruits, quince, apple, and pear suffer about in the 
order named. Service (figs. 18, 19), wild crab, mountain ash, thorns 
of different species, and chokeberry are the wild or native trees 
which serve as its food. These wild trees are named, also, about in 
1Amelanchier canadensis, 
